Brown (left) and Bush in London (epa)
U.S. President George W. Bush began the last day of his farewell tour of Europe with good news from Britain's prime minister.

Gordon Brown said London would impose further economic sanctions on Iran to help persuade it to suspend its nuclear program, and he promised to set no timelines for withdrawals of his country's forces from Iraq.

"If Iran continues to ignore United [Nations] resolutions, to ignore our offers of partnership, we have no choice but to intensify sanctions. And so today Britain will urge Europe and Europe will agree to take further sanctions against Iran," Brown said at a joint news conference with Bush.

"First of all, we will take action today that will freeze the overseas assets of the biggest bank in Iran, the Bank Melli, and second, action will start today for a new phase of sanctions on oil and gas," he added.

Washington wants to build European support for new sanctions against Tehran if it rejects incentives to give up uranium enrichment.

Bush's meetings in London come as Iran on June 14 ruled out suspending uranium enrichment, despite a renewed offer by the five UN permanent Security Council members and Germany to help it develop a civilian nuclear program in exchange for abandoning its enrichment efforts.

Iran has now got its answer from Brown, underlining support that Bush has already received earlier in his trip from Italian Prime Minister Silvio Berlusconi, French President Nicolas Sarkozy, and German Chancellor Angela Merkel. All have said they share Washington's goal of assuring Tehran does not obtain nuclear weapons.

The U.S. and European leaders hope this will add pressure on Iran to soften its approach toward the incentives offer or build international support for a third round of sanctions at the United Nations.

'No Artificial Timetables' In Iraq

Also on Bush's agenda in London is Iraq. In an interview with a British newspaper, "The Observer," on June 15, Bush urged London not to withdraw its troops from southern Iraq until the security situation there improves.

At the June 16 news conference, Bush said most of the 30,000 U.S. troops sent to Iraq last year to mount the so-called "surge" will have been withdrawn by next month. Further pullouts, he said, will depend on the evolving state of Iraq's security.

"As the Iraqis are trained up, as they are taking more responsibility, as the security situations decline, as the economy is improved, as political reconciliation is taking place, we can bring more troops home," Bush said.

"That's the whole purpose of the strategy -- and so, give the Iraqis more responsibility, let them be in more charge of their own security and their own government, and that's what's happening," he added.

Again, Brown said the British approach to withdrawals would be the same.

"In Iraq, there is a job to be done, and we will continue to do the job, and there's going to be no artificial timetable," Brown said. "And the reason is that we are making progress, making progress in the Iraqis themselves being trained up to run their own armed forces and, of course, to be the policemen and -women in their areas."

Britain has about 4,200 troops in the south and London has suggested previously that it could pull them all out by the end of this year.

Britain is the United States' closest ally in Iraq, took part in the 2003 invasion to topple Saddam Hussein, and has invested lives and money in efforts to stabilize the south. But the troop deployment in Iraq is unpopular with the British public and thus politically sensitive for Brown.

Thousands of antiwar protesters made their presence felt as Bush arrived in London on June 15. Police said 25 protesters were arrested and 10 officers were injured in scuffles.More Troops To Afghanistan

Brown and Bush also spoke of Afghanistan, and Afghan President Hamid Karzai's threat to send troops into neighboring Pakistan in pursuit of Taliban and allied forces that have been making cross-border attacks in Afghanistan.

Bush said he'd try to calm what he called a "testy situation" between Pakistan and Afghanistan, and he urged both countries' intelligence services to share information they have on Taliban leaders.

Brown, meanwhile, promised to send more troops, though he didn't say how many or how soon.

"The reason is that we want to help the Afghans train up their own army and their own police forces and the reason is we want to have better equipment in Afghanistan in the future," Brown said.

"And therefore there is going to be reconfiguration of our troops, there will be some coming out and some more going in and overall increasing the numbers so that we have the highest level of troops in Afghanistan."

After London, Bush travels to Belfast in Northern Ireland for talks with officials. There he is expected to urge Britain to transfer more powers over the police and the judiciary to local authorities as a way to help defuse decades-old separatist tensions.

Bush then returns to Washington for the last months of his presidential term. He is due to leave office in January 2009.